package com.nuanshui.framework.security;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * RSA工具类
 * 
 * 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式
 * 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密，
 * 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全 
 */
public class RSA {

	/**
     * 加密算法RSA 
     */  
    public static final String KEY_ALGORITHM = "RSA";
    /**
     * 获取公钥的key 
     */  
    private static final String PUBLIC_KEY = "RSAPublicKey";  
      
    /**
     * 获取私钥的key 
     */  
    private static final String PRIVATE_KEY = "RSAPrivateKey";  
      
    /**
     * RSA最大加密明文大小 
     */  
    private static final int MAX_ENCRYPT_BLOCK = 117;  
      
    /**
     * RSA最大解密密文大小 
     */  
    private static final int MAX_DECRYPT_BLOCK = 128;  
    
	/**
	 * 签名算法
	 */
	public static final String SIGN_ALGORITHMS = "SHA1WithRSA";
	/**
	 * 签名算法
	 */
	public static final String MD5_SIGN_ALGORITHMS = "MD5WithRSA";
	
    

	/**
	 * RSA签名
	 * 
	 * @param content
	 *            待签名数据
	 * @param privateKey
	 *            翰鑫私钥
	 *            
	 * @return 签名值
	 */
	public static String md5Sign(String content, String privateKey)
			throws Exception {

		PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(
				Base64.decode(privateKey));
		KeyFactory keyf = KeyFactory.getInstance(KEY_ALGORITHM);
		PrivateKey priKey = keyf.generatePrivate(priPKCS8);

		java.security.Signature signature = java.security.Signature
				.getInstance(MD5_SIGN_ALGORITHMS);

		signature.initSign(priKey);
		signature.update(content.getBytes("utf-8"));
		byte[] signed = signature.sign();

		return Base64.encode(signed);
	}
	
	/**
	 * RSA签名
	 * 
	 * @param content
	 *            待签名数据
	 * @param privateKey
	 *            翰鑫私钥
	 *            
	 * @return 签名值
	 */
	public static String sign(String content, String privateKey)
			throws Exception {

		PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(
				Base64.decode(privateKey));
		KeyFactory keyf = KeyFactory.getInstance(KEY_ALGORITHM);
		PrivateKey priKey = keyf.generatePrivate(priPKCS8);

		java.security.Signature signature = java.security.Signature
				.getInstance(SIGN_ALGORITHMS);

		signature.initSign(priKey);
		signature.update(content.getBytes("utf-8"));
		byte[] signed = signature.sign();

		return Base64.encode(signed);
	}
	
   /**
	* RSA验签名检查
	* 
	* @param content 待签名数据
	* @param sign 签名值
	* @param partnerPublicKey 商户公钥
	* 
	* @return true:验证通过 false:验证失败
	*/
	public static boolean verify(String content, String sign, String partnerPublicKey){
		try{
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
	        byte[] encodedKey = Base64.decode(partnerPublicKey);
	        PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
			java.security.Signature signature = java.security.Signature
			.getInstance(SIGN_ALGORITHMS);
		
			signature.initVerify(pubKey);
			signature.update( content.getBytes("utf-8") );
		
			boolean bverify = signature.verify( Base64.decode(sign) );
			return bverify;
			
		}catch (Exception e){
			e.printStackTrace();
		}
		
		return false;
	}
	
    /** 
     * 生成密钥对(公钥和私钥) 
     *  
     * @return 
     * @throws Exception 
     */  
    public static Map<String, Object> genKeyPair() throws Exception {  
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);  
        keyPairGen.initialize(1024);  
        KeyPair keyPair = keyPairGen.generateKeyPair();  
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();  
        Map<String, Object> keyMap = new HashMap<String, Object>(2);  
        keyMap.put(PUBLIC_KEY, publicKey);  
        keyMap.put(PRIVATE_KEY, privateKey);  
        return keyMap;  
    }  
    
    public static void main(String[] args) {
    	try {
    		Map<String, Object> map = RSA.genKeyPair();
    		System.out.println(Base64.encode(((RSAPrivateKey)map.get(PRIVATE_KEY)).getEncoded()));
    		System.out.println(Base64.encode(((RSAPublicKey)map.get(PUBLIC_KEY)).getEncoded()));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
    /**
     * 私钥解密 
     *  
     * @param encryptedData 已加密数据 
     * @param privateKey 私钥(BASE64编码) 
     * @return 
     * @throws Exception 
     */  
    public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)  
            throws Exception {  
        byte[] keyBytes = Base64.decode(privateKey);  
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);  
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);  
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());  
        cipher.init(Cipher.DECRYPT_MODE, privateK);  
        int inputLen = encryptedData.length;  
        ByteArrayOutputStream out = new ByteArrayOutputStream();  
        int offSet = 0;  
        byte[] cache;  
        int i = 0;  
        // 对数据分段解密  
        while (inputLen - offSet > 0) {  
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {  
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);  
            } else {  
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);  
            }  
            out.write(cache, 0, cache.length);  
            i++;  
            offSet = i * MAX_DECRYPT_BLOCK;  
        }  
        byte[] decryptedData = out.toByteArray();  
        out.close();  
        return decryptedData;  
    }  
  
    /**
     * 公钥解密 
     *  
     * @param encryptedData 已加密数据 
     * @param publicKey 公钥(BASE64编码) 
     * @return 
     * @throws Exception 
     */  
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)  
            throws Exception {  
        byte[] keyBytes = Base64.decode(publicKey);  
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);  
        Key publicK = keyFactory.generatePublic(x509KeySpec);  
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());  
        cipher.init(Cipher.DECRYPT_MODE, publicK);  
        int inputLen = encryptedData.length;  
        ByteArrayOutputStream out = new ByteArrayOutputStream();  
        int offSet = 0;  
        byte[] cache;  
        int i = 0;  
        // 对数据分段解密  
        while (inputLen - offSet > 0) {  
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {  
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);  
            } else {  
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);  
            }  
            out.write(cache, 0, cache.length);  
            i++;  
            offSet = i * MAX_DECRYPT_BLOCK;  
        }  
        byte[] decryptedData = out.toByteArray();  
        out.close();  
        return decryptedData;  
    }  
    
    /**
     * 公钥加密 
     *  
     * @param data 源数据 
     * @param publicKey 公钥(BASE64编码) 
     * @return 
     * @throws Exception 
     */  
    public static byte[] encryptByPublicKey(byte[] data, String publicKey)  
            throws Exception {  
        byte[] keyBytes = Base64.decode(publicKey);  
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);  
        Key publicK = keyFactory.generatePublic(x509KeySpec);  
        // 对数据加密  
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());  
        cipher.init(Cipher.ENCRYPT_MODE, publicK);  
        int inputLen = data.length;  
        ByteArrayOutputStream out = new ByteArrayOutputStream();  
        int offSet = 0;  
        byte[] cache;  
        int i = 0;  
        // 对数据分段加密  
        while (inputLen - offSet > 0) {  
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {  
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);  
            } else {  
                cache = cipher.doFinal(data, offSet, inputLen - offSet);  
            }  
            out.write(cache, 0, cache.length);  
            i++;  
            offSet = i * MAX_ENCRYPT_BLOCK;  
        }  
        byte[] encryptedData = out.toByteArray();  
        out.close();  
        return encryptedData;  
    }  
  
    /**
     * 私钥加密 
     *  
     * @param data 源数据 
     * @param privateKey 私钥(BASE64编码) 
     * @return 
     * @throws Exception 
     */  
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey)  
            throws Exception {  
        byte[] keyBytes = Base64.decode(privateKey);  
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);  
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);  
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());  
        cipher.init(Cipher.ENCRYPT_MODE, privateK);  
        int inputLen = data.length;  
        ByteArrayOutputStream out = new ByteArrayOutputStream();  
        int offSet = 0;  
        byte[] cache;  
        int i = 0;  
        // 对数据分段加密  
        while (inputLen - offSet > 0) {  
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {  
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);  
            } else {  
                cache = cipher.doFinal(data, offSet, inputLen - offSet);  
            }  
            out.write(cache, 0, cache.length);  
            i++;  
            offSet = i * MAX_ENCRYPT_BLOCK;  
        }  
        byte[] encryptedData = out.toByteArray();  
        out.close();  
        return encryptedData;  
    }  
  
    /**
     * 获取私钥 
     *  
     * @param keyMap 密钥对 
     * @return 
     * @throws Exception 
     */  
    public static String getPrivateKey(Map<String, Object> keyMap)  
            throws Exception {  
        Key key = (Key) keyMap.get(PRIVATE_KEY);  
        return Base64.encode(key.getEncoded());  
    }  
  
    /**
     * 获取公钥 
     *  
     * @param keyMap 密钥对 
     * @return 
     * @throws Exception 
     */  
    public static String getPublicKey(Map<String, Object> keyMap)  
            throws Exception {  
        Key key = (Key) keyMap.get(PUBLIC_KEY);  
        return Base64.encode(key.getEncoded());  
    }  
    
}
